1. Field of the Invention
The present invention generally relates to a method, system and program product for modifying content usage conditions during broadcast (uni-directional) content distribution. More specifically, the present invention allows content usage conditions placed on digital content to be modified at various points during broadcast distribution of the digital content.
2. Background Art
As the use of digital technology becomes more pervasive, content such as television programming, music and movies are being increasingly delivered to consumers in digital format. One form of digital delivery is known as broadcast encryption whereby encrypted content can be received and decrypted without requiring two way communications between the recipient and the source. In particular, the encrypted content is transmitted from the source to the recipient with all information necessary to decrypt and utilize the content. This eliminates the need for follow-up communications from the recipient to the source. Conversely, many existing public distribution systems require two way communications (i.e., a “handshake”). However, in some applications, having a return channel for the handshake can be impossible, or at least very expensive.
A fundamental aspect of broadcast encryption schemes that enable one-way communication is the concept of a key management block (also referred to as a session key block or a media key block). The key management block allows compliant devices to calculate a cryptographic key using their internal device keys. At the same time, if a known circumvention device tries to perform the same calculation, it is misled by data in the key management block and will arrive at the wrong answer for the key.
One advantage of delivering content in a digital format, is the capability to impose usage conditions on the content. Specifically, the content can be packaged or “embedded” with usage conditions (e.g., copy controls) that help prevent the content from being illegally copied or otherwise exploited in its original form. Currently, many consumers can obtain content without making a legal purchase. This generally occurs when an individual obtains the content, and then reproduces it for distribution to third parties. In many of such cases, one copy of the content was legally purchased, but then abused by being reproduced and distributed without the requisite licensing fees being paid to a content owner (e.g., a movie studio) and/or a content service provider (e.g., a cable service provider). Accordingly, in an effort to limit losses, content owners have begun to “embed” various content usage conditions within the content.
Previously, if the content was to be encrypted or otherwise protected by the content owner, content usage conditions had to be defined at the origin of distribution. That is, the content usage conditions had to be defined and embedded prior to distribution of the encrypted content. To this extent, it was generally convenient for a content owner to produce a single piece of content and include the various usage conditions for all possible usage scenarios. For example, a movie might have usage conditions that specify, in a pay-per view application, “do not copy,” whereas in a normal premium cable channel broadcast the usage conditions might state “copy once.” However, it is difficult for a downstream device such as a video recorder to know which of the two situations applies. On the other hand, a content service provider would know which content usage conditions apply for a given instance. Accordingly, providing the content service provider with the capability to modify the content usage conditions would be very helpful as it could simply delete the irrelevant conditions. Moreover, modification of the content usage conditions can be valuable to a content service provider who may desire to limit distribution of content, which might not have been addressed by the content owner. In addition, with the growth of consumer home networks, it may be advantageous to provide end-users/consumers with the capability to modify content usage conditions, in a controlled way, within their respective home networks.
In view of the foregoing, there exists a need for a method, system and program product for modifying content usage conditions during one-way or broadcast content distribution. A further need exists for a content service provider and/or a consumer to be able to receive the content in a protected form, and modify the content usage conditions. Still yet, a need exists for a content service provider and/or a consumer to be able to modify content usage conditions according to an agreed-upon set of rules.